Dephosphorylation of insulin receptor substrate 1 by the tyrosine phosphatase PTP2C

J Biol Chem. 1994 Jun 3;269(22):15833-7.

Abstract

The phosphotyrosine (Tyr(P)) form of insulin receptor substrate 1 (IRS-1) is a key component in insulin signaling. Our previous study revealed that Tyr(P) IRS-1 binds to the widely distributed tyrosine phosphatase PTP2C through the src homology 2 (SH2) domains of the latter. In the present study, we examined the activity of this enzyme and of a truncated form lacking the SH2 domains (delta PTP2C) toward IRS-1 and also toward the cytoplasmic domain of the insulin receptor. Tyr(P) IRS-1 was prepared by phosphorylation of recombinant IRS-1 with recombinant cytoplasmic insulin receptor kinase (CIRK). PTP2C rapidly dephosphorylated Tyr(P) IRS-1; dephosphorylation by delta PTP2C was approximately one-third as fast. Other substrates, including Tyr(P) CIRK, were not dephosphorylated as rapidly by PTP2C; moreover, delta PTP2C was at least 10 times more active than PTP2C toward CIRK and other substrates. These results indicate that the binding of Tyr(P) residues on IRS-1 to the SH2 domain(s) of PTP2C enhances its activity toward IRS-1 and suggest that PTP2C is the phosphatase responsible for the dephosphorylation of IRS-1 in vivo. In addition, with the expectation that a PTP2C-resistant form of IRS-1 will be useful in investigations of IRS-1 function, we determined that IRS-1 can be thiophosphorylated with adenosine 5'-O-(3-thiotriphosphate) and CIRK and that this form of IRS-1 is resistant to PTP2C.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Humans
  • Insulin Receptor Substrate Proteins
  • Intracellular Signaling Peptides and Proteins
  • Kinetics
  • Moths
  • Phosphoproteins / biosynthesis
  • Phosphoproteins / isolation & purification
  • Phosphoproteins / metabolism*
  • Phosphorylation
  • Phosphotyrosine
  • Protein Tyrosine Phosphatase, Non-Receptor Type 11
  • Protein Tyrosine Phosphatase, Non-Receptor Type 6
  • Protein Tyrosine Phosphatases / metabolism*
  • Rats
  • Receptor, Insulin / biosynthesis
  • Receptor, Insulin / metabolism
  • Recombinant Proteins / metabolism
  • SH2 Domain-Containing Protein Tyrosine Phosphatases
  • Substrate Specificity
  • Transfection
  • Tyrosine / analogs & derivatives
  • Tyrosine / analysis
  • Tyrosine / metabolism

Substances

  • IRS1 protein, human
  • Insulin Receptor Substrate Proteins
  • Intracellular Signaling Peptides and Proteins
  • Irs1 protein, rat
  • Phosphoproteins
  • Recombinant Proteins
  • Phosphotyrosine
  • Tyrosine
  • Receptor, Insulin
  • PTPN11 protein, human
  • PTPN6 protein, human
  • Protein Tyrosine Phosphatase, Non-Receptor Type 11
  • Protein Tyrosine Phosphatase, Non-Receptor Type 6
  • Protein Tyrosine Phosphatases
  • Ptpn11 protein, rat
  • Ptpn6 protein, rat
  • SH2 Domain-Containing Protein Tyrosine Phosphatases